HF scientific Micro200BW Turbidimeter - 0 -1000 NTU - Manual (Page 47)

Page 33
MICRO 200 BW 0 - 1000 NTU (5/05)
Rev. 3.1
VIII. OPTIONS
BACKWASH
A. INSTALLATION
1. Backwash Interface
To monitor backwash using the MICRO 200 BW, one
backwash interface and one backwash sensor is re-
quired for each analyzer. Refer to figure 16 for the
outline of the backwash interface. Power requirements
are 12 VA at 110 - 120 VAC or 220 - 240 VAC. The
voltage may be changed using the selector switch
located inside the interface housing. See figure 17 for
details. The interface may be mounted up to 320 feet
(91.4 m) away from the backwash sensor. The signal
is sent to the MICRO 200 BW analyzer via BNC
connectors through up to 1000 feet (304.8 meters) of
coaxial cable (Catalog No. 20849). Refer to figure 14
for the analyzer BNC cable connection.
Figure 14
Analyzer BNC Connection
2. Junction Box
This option, HF Catalog No. 19805, may be used to
extend the backwash sensor cable to a total length of
350 feet (106.7 meters), as measured from the sensor to
the backwash interface. The junction box is weather
tight and may be mounted outside. Refer to figure 18 for
outline dimensions. For wire connections refer to fig-
ure 19. Extension cable may be ordered using HF
Catalog No. 20848.
3. Backwash Sensor
There are two standard methods of installing this sen-
sor, channel mounting and extension handle mount-
ing. Both of these will be described below. If alternate
methods of mounting are required, please consult HF
scientific inc.
When choosing an installation site for the sensor there
are several things to consider. Since filters rarely will
backwash consistently or uniformly, a site should be
chosen that best averages the backwash water over the
cycle. The sensor should also be located as close to the
backwash filter as possible to reduce the time delay of
the water sample. This will give the operator a correct
picture as to how the backwash is proceeding and when
it is complete. Refer to figure 20 for sensor outline
dimensions.
a. Channel Mounting
This method can be used when the area above the end
of the channel is easily accessible. This allows cleaning
of the sensor or calibrating by lifting the sensor up by
its cable and lowering it back into place when you are
finished. Since the sensor is not affected by sunlight, a
lightshield is not required. An installation kit is avail-
able from HF scientific, HF Catalog No. 50345 which
includes the sensor chamber, a stainless steel bracket,
and mounting clamps. The user must supply PVC
piping, bolts and anchors. Refer to Figure 21.
b. Extension Handle Mounting
This method allows the user to adjust the sensor posi-
tioning to optimize the sampled water. An installation
kit is available from HF scientific, HF Catalog No.
50356 which includes sensor end baffles, hose clamps,
and a pipe adapter. The user must supply the extension
pipe such as galvanized steel ½” to 1½” in diameter
(12.7 mm - 38.1 mm) and any additional mounting
deemed necessary for upper end.
1. The slot for the outlet baffle must be positioned in
a vertical axis at the top.
2. Remove all rough edges from the pipe to prevent
cable damage.
3. Attach the sensor to the pipe adapter with hose
clamps.
4. Sensor cable can be wrapped around the pipe. If
the pipe diameter permits, the cable can be threaded
through the pipe.
5. Don’t pull the cable too sharply through the pipe,
use a large radius bend instead.
In operation, some experimentation will be needed
during backwash to achieve optimal results. Note that
the adapter has a pivot to allow the sensor to lay parallel
to the bottom. Refer to figure 22.
B. BACKWASH SENSOR CONNECTIONS
The Backwash sensor is supplied with a 30 foot (9.1
meters) cable. This cable connects at TB2 of the Back-
wash Interface. The cable should first be inserted
through the strain relief fitting of the case. At this point
the outer jacket of the cable should be stripped back